Fluidized coal carbonization

Claim 1

In the multistage fluidized carbonization of coal to produce oil, gas and char wherein the coal is: 1. Heated in a first stage below its fusion temperature under oxygen free conditions in a first fluidized bed formed by passing an inert gasiform stream upwardly through the stage to maintain the coal in the fluidized state; 2. In at least a second stage passing the so-treated coal into at least one other fluidized bed which is fluidized by the gaseous overheads from the subsequent stages at a temperature above that of the first bed and below the fusion point of the solids fed to that stage, under oxygen-free conditions, for a time sufficient to remove nearly all of the volatiles from the coal condensable oily liquids, and 3. In a final stage passing the thus-treated coal into a final fluidized bed which is fluidized by an oxygen-containing gas at a still higher temperature, to substantially devolatilize the coal, the improvement of recovering sensible heat from the overheads of stage 1 comprising the steps (1) providing a fluidized drying zone to receive the particulate coal feed; (2) using the stage 1 overheads as the fluidizing atmosphere in step (1) to heat and dry the particulate coal feed while maintaining the vapor pressure of the oil in the drying zone at a value of under 10 mm; (3) conveying the dried coal to stage 1; and (4) recovering oil from the overheads of the fluidized drying zone.